Android Thread for a Timer

Android - Run a thread repeatingly within a timer

Just simply use below snippet

private final Handler handler = new Handler();
private Runnable runnable = new Runnable() {
    public void run() {
         //
         // Do the stuff
         //

         handler.postDelayed(this, 1000);
    }
};
runnable.run();

To stop it use

handler.removeCallbacks(runnable);

Should do the trick.

How to stop the Timer thread?

Given that Thread.stop is deprecated, the only option you have is to add some signalling of your own, like a boolean variable that you set when you want it to stop.

e.g.

boolean stop = false;
public void startTimer() {
    startTime = System.currentTimeMillis();
    final Handler handler = new Handler();
    task =new Thread() {
        @Override
        public void run() {
            if (stop) {
                return;
            }
            long millis = System.currentTimeMillis()-startTime;
            long secs = millis / 1000 % 60; // seconds, 0 - 59
            long mins = millis / 1000 / 60 % 60; // total seconds / 60, 0 - 59
            long hours = millis / 1000 / 60 / 60; // total seconds / 3600, 0 - limitless

            timeString = String.format("%02d:%02d:%02d", hours, mins, secs);
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mtvtimer.setText(timeString);
                }
            });

           handler.postDelayed(task, 1000);
    }

And from somewhere else, you set stop = true to stop it.
(this is a rough example code, just to get the idea through)

Android Timer instead of Thread.sleep for sending binary code via LED

Thread.sleep caused your current Thread to sleep at least 100ms. This doesn't mean that in 100 ms your next statement will be executed. Timer uses another thread, so if you need to perform some action on UI thread, you have to post the message to UI thread. If you need delayed message without blocking the UI thread - use Handler.post message:

Handler handler = new Handler();
try {
    for (int a = 1; a <= 3; a++) {
        for (int i = 0; i < data.length(); i++) {

            if (data.charAt(i) == '1') {
                handler.postDelayed(new Runnable() {
                    @Override public void run() {
                        camera.setParameters(parametersOn);
                        camera.startPreview();
                    }
                }, i * 100);
            } else {
               handler.postDelayed(new Runnable() {
                    @Override public void run() {
                        camera.setParameters(parametersOff);
                        camera.startPreview();
                    }
                }, i * 100);
            }
        }
    }
} catch (Exception e) {

}

Having A Timer Use The Main Thread in Kotlin

You can extend timerTask to return on the main thread.
Basically, get a Hander that runs on the main thread:

Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
     public void run() {
          // UI code goes here
     }
});

Then have timerTask execute its function parameter in the run method above. Alternatively, you can just have that code in you lambda or even use activity.runOnUiThread(). Really the correct solution comes down to how often you do this in your code, of it's a one off just use runOnUiThread.

Android how to run thread for each 25 ms?

Use a ScheduledExecutorService:

Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate(/* Your Runnable */, 0, 25, TimeUnit.MILLISECONDS);

Or RxJava:

Flowable.interval(0, 25, TimeUnit.MILLISECONDS).subscribe(/* Code to execute */);

Android CountDownTimer Class Lagging Main Thread

I decided to take a different approach which has served my purposes very well. No lag or thread issues and can easily be restarted over and over. Hope this helps someone out.

int startCountdown = 5;
int currentCountdown;
Handler countdownHandler = new Handler();
Timer countdownTimer = new Timer();
public void startCountdownTimer() {
    currentCountdown = startCountdown;
    for (int i = 0; i <= startCountdown; i++) {
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                countdownHandler.post(doA);
            }
        };
        countdownTimer.schedule(task, i * 1000);
    }
}
final Runnable doA = new Runnable() {
    @Override
    public void run() {
        if (currentCountdown != 0) {
            tvTextView.setText("" + currentCountdown);
        currentCountdown--;
        } else {
            currentCountdown = startCountdown;
            startCountdownTimer();
        }
    }
};